Fuel vapor emission control canisters generally and their use in controlling emissions of fuel vapors from motor vehicles are well known to the skilled of the art. Carbon canister systems are known for storing fuel vapors emitted from an automotive-type fuel tank or carburetor float bowl or other similar fuel reservoir to prevent emissions into the atmosphere of such fuel vapors. These systems usually consist of a canister containing carbon or other medium which will releasably adsorb the fuel vapors. The canister would have an inlet from the fuel tank or other reservoir, the fuel vapors flowing either by gravity or under vapor pressure into the canister to be adsorbed by the filter medium therein and stored. The canister also would have a fresh air inlet and, further, a purge line connecting the canister to the carburetor or engine intake manifold. During operation of the engine, vacuum in the intake manifold draws fresh air through the canister to the engine, thereby desorbing the filter medium of the fuel vapors.
Typically, a fuel vapor emission control canister houses a bed of an adsorbent material, such as granulated charcoal or the like, often in conjunction with other filtering means. Exemplary of such technology is that taught in U.S. Pat. No. 4,568,797 to Brand; U.S. Pat. No. 4,454,849 to Mizuno et al; and U.S. Pat. No. 4,326,489 to Heitert.
The vapor adsorbing capacity of the adsorbent bed is limited, and typically, as noted above, a flow of atmospheric air is drawn by vacuum through the canister to the vehicle engine during the operation of the motor vehicle engine to at least partially rejuvenate the adsorptive medium. A large capacity adsorptive bed must nevertheless be provided to eliminate or at least reduce the amount of fuel vapors which are emitted to the atmosphere, e.g., when the vehicle remains unused for long periods or is used in an area of high ambient temperatures. The "packaging" of a large capacity fuel vapor emission control canister in a motor vehicle, that is, the positioning of one or more such canisters within a vehicle, presents a significant problem to vehicle manufactures, especially in view of the ever increasing importance of efficient use of vehicle space to accommodate vehicle down-sizing.
It is an object of the present invention to provide a motor vehicle fuel vapor emission control assembly wherein the adsorptive bed is packaged in the motor vehicle in a highly space efficient manner. This and other objects and advantages of the present invention will be apparent in view of the following disclosure.